Accessory hemiazygos vein of posterior thoracic wall

Location

It is also known as superior hemiazygos vein . it lies on the left side only and corresponds to the upper part of azygos vein

Tributaries

·         5^th to 8^th left posterior intercostals vein

·         Left bronchial veins (occationally )

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Formation

The accessory hemiazygos vein is formed by the confluence of the middle left posterior intercostal veins. 

Course

It descends to the left of midline, adjacent to the thoracic vertebrae and crosses posteriorly to the aorta at the level of T7-8 to drain into the azygos vein. It normally anastomoses with the left superior intercostal vein.

Variant anatomy

·         drains via a common trunk with the hemiazygos vein into the azygos vein

·         forms a common trunk with the hemiazygos vein that passes anterior to the aorta called the interazygos vein 

·         drains directly into the left brachiocephalic vein (rare) 

Drainage area

It drains the left superior hemithorax.